Microstructure mechanism, cyclic deformation behavior of an Fe-Ni-Cr alloy considering non-Masing behavior

•Non-Masing behavior of Sanicro 25 alloy during LCF was investigated.•Non-Masing behavior was explained based on the EBSD analysis.•Theoretical relationship of cyclic stress and plastic strain considering non-Masing behavior was derived.•Effect of non-Masing behavior on the stress amplitude was discussed. The non-Masing behavior of Sanicro 25 alloy was studied during high-temperature low-cycle fatigue (700 °C). The results showed that Sanicro 25 alloy exhibits the non-Masing behavior when total strain amplitude (εa) increased. The analysis of stable hysteresis loops showed that the stress amplitude (σa) increased with increasing εa. At the stable cyclic stage, the rate of increase in σa with number of cycles increased when εa increased. Based on the EBSD observation, the Geometrically Necessary Dislocation (GND) density increased as εa increased. The region of high dislocation density was distributed along the grain boundaries, which led to the increasing flow stress. The fraction of twin boundaries decreased and the grain size increased with increasing εa, which led to a more obvious cyclic yielding stage. Therefore, the non-Masing behavior occurred at a relatively high εa. Considering the influence of non-Masing behavior on the probability density function relative to the cyclic yield level, the relationship of cyclic stress and plastic strain with the increment of the proportional stress limit δσ0 and Bauschinger strain β was established. σa increases linearly with increasing δσ0. σa decreases with increasing β.